Indoor air pollution is a known and persistent problem that affects people's health and well-being. A particular issue is the indoor air pollution with formaldehyde gas. For instance, the indoor air in many places suffers from formaldehyde pollution due to the widespread unregulated use of low-cost building and decoration materials comprising urea-formaldehyde resins. Adequate ventilation with outdoor air is a good remedy to remove the formaldehyde pollution. But the mechanical ventilation with filtered and temperature-conditioned outdoor air is only rarely encountered in common homes and apartments which mostly rely on natural ventilation. Natural ventilation becomes less desirable in case the outdoor air is polluted. Furthermore, people tend to minimize the natural ventilation level anyway when the outdoor temperature is uncomfortable.
Formaldehyde can be removed from air through the use of chemically-impregnated filters. These filters comprise specific impregnated reagents that exhibit specific chemical or physical interactions with target gaseous pollutants such as formaldehyde, so as to remove formaldehyde from air. Considering other target gaseous pollutants, such as acidic gases (e.g., HNOx, SO2, organic acids) or alkaline gases (e.g., NH3, amines), corresponding alkaline or acidic reagents, respectively, can be used for their removal from air.